This invention relates to sensing apparatus. More particularly, it is concerned with sensing apparatus for monitoring the operation of electrical appliances.
In certain situations it is desirable to monitor the operation of electrical appliances. More specifically, it may be desirable to determine the presence or absence of activity within a dwelling unit by monitoring the turning off and/or turning on of one or more household appliances.
A system for passively monitoring the activities of certain persons, particularly elderly persons, is described in U.S. Pat. No. 3,885,235. This system monitors the occurrence of certain routine activities and provides appropriate indications in the event that such routine activities do not occur within a preselected period of time. The activities monitored include the operation of various electrical appliances such as radios, television sets, and other household appliances. Sensing apparatus are employed in conjunction with the selected appliances to note the operation of each appliance and in response to its operation to provide an indication for processing by the system.